Re : Blank pages - no error msgs
tiki-install.php shouldn't get you to tiki-index.php automatically.
Did you try running your DB on another 1.8.0 install? If it succeeds you'll probably be on your own and want to debug yourself. You should look in your servers' logs.
If there's still no clue, I think a good starting point is tiki-phpinfo.php. This is a very simple script. The only big stuff is tiki-setup.php inclusion 
Check if it works. If it doesn't, remove the die so that the phpinfo() should be called and remove stuff from tiki-setup.php until it works.
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;){kind=link}